The proposed research would evaluate the feasibility of a three-dimensional ultrasound imaging system for the male prostate. The system would be capable of extracting three-dimensional images of the prostate from sets of two-dimensional ultrasound images obtained via a special-purpose transrectal ultrasound probe. The extraction of the three-dimensional images from the two-dimensional image sets will be performed by finding the edges of the gland in each of the two-dimensional images. Such a low-cost system would enhance the early detection of prostate cancer and yield new, non-invasive methods for monitoring gland pathology during radiation therapy. In order to obtain image sets for study, one of the applicant's PROSCAN Bi- Plane Imaging System would be modified to produce either multiple transverse or multiple sagittal images of the prostate. This system currently has the capability of producing both longitudinal and transverse images of the prostate using a single transrectal probe. Both the probe and the supporting electronics package would be modified so that two-dimensional image sets could be obtained by a practicing physician. Several different edge detection algorithms will be investigated to determine the feasibility of three-dimensional image extraction from the two-dimensional image sets.